Typical key operated padlocks are manufactured to operate in one of two distinct manners or "functions": a non-key retaining function and a key retaining function.
In a padlock designed to have non-key retaining ("NKR") function, the key may be removed while the padlock is unlocked. The padlock may then be locked at any time by pushing the shackle into the padlock body, allowing the padlock mechanism to automatically lock the padlock. This padlock, therefore, does not "retain" the key while the padlock is unlocked.
In a padlock designed to have a key-retaining ("KR") function, the padlock mechanism prevents the key from being removed from the padlock while the padlock is unlocked. The padlock mechanism allows the key to be removed only when the padlock shackle is returned to the locked position in the padlock body. This padlock, therefore, "retains" the key while the padlock is unlocked.
There are practical, functional and security requirements for both functions. Heretofore, users of padlocks, after determining their padlock function requirements, would then procure padlocks of the appropriate function. Manufacturers produce padlocks of one function or the other to fulfill these various user requirements. This causes manufacturers, lock-smiths and padlock suppliers to stock double inventories of padlocks, one set of NKR padlocks and one set of KR padlocks, to satisfy padlock user needs.
Situations arise where an unauthorized person obtains control of the key to a padlock or a master key for a series of padlocks, or has a duplicate key made surreptitiously, so that he is able, at his convenience, to open the padlock or padlocks and gain unauthorized entry to the building or compartment protected by the padlock. In other instances, it may be desirable that a padlock be operated by the same key that is used for other locks on residential, commercial, industrial, government and military buildings or compartments. In this case it is necessary to remove the present cylinder from the padlock and insert into the padlock body a new cylinder of the type required to meet the new keying specification. In all these situations, it is necessary to remove the cylinder from the padlock for servicing or replacement. All of such situations are conveniently provided for by the present improved dual function padlock with removable cylinder mechanism.
Typical prior art padlock patents show examples of single function padlocks, in either a NKR or KR design. U.S. Pat. No. 3,882,699 discloses a non-key retaining function padlock. U.S. Pat. No. 4,112,715 to Uyeda discloses a key-retaining function padlock. U.S. Pat. No. 4,290,280 to Yun discloses a non-key retaining function padlock. U.S. Pat. No. 4,138,868 to Richards discloses a single function, non-key retaining only padlock.
The prior art as a body discloses no padlock structure in which dual function capability is accomplished. There is a need in the art for a padlock that is formed to accept generic cylinders, the cylinders being of a design and type readily available and produced by manufacturers to standard dimensions commonly found in residential and commercial applications and adaptable to all keyways and keying systems in general use, but allowing dual function selection in a single padlock.
It is an object of the present invention to provide a single padlock in which the required function can be selected at the time of installation. Thus, it would no longer be necessary for padlock suppliers to stock two separate inventories of padlocks, one in a NKR function and one in a KR function, as is currently necessary to provide the choice of the particular function required by padlock users.
It is an advantage of the present invention that by providing a padlock with a removable key-actuated cylinder mechanism of a generic type, the owner of the padlock or a technician may, for reasons of security or convenience, change the key, remove the cylinder mechanism to repair the same, convert one or a group of padlocks to various keying specifications replace the cylinder in the padlock with another cylinder providing for a key change, or perform work on the padlock which involves a change or repair of the cylinder or padlock mechanism.
It is a further object of the present invention to provide a dual function, removable cylinder, re-keyable padlock of such structure as to accept and be operated by an s unlimited variety of standard dimensioned, generic lock cylinders produced by manufacturers of locks and keying systems.
It is a further object of the present invention to provide a padlock with dual function capability, whereby a padlock supplier would no longer have to stock two distinct padlock models to fulfill customer needs. One padlock of the dual function type would replace the previous two product lines, with obvious cost savings. By having a dual function padlock, where either the non-key retaining function or the key retaining function could be easily selected at the time of installation by means of a simple arrangement of interior parts, the padlock supplier could fulfill customer requirements, while vastly reducing inventory, resulting in lower costs to both the supplier and the customer.
Manufacturers of locks and keying systems have standardized many types of key operated lock cylinders to allow interchangeability with various lock mechanism and adaptability to a variety of keying types and systems meeting requirements of security and convenience. The present invention furthers these goals of standardization and convenience of adapting to various keying systems by accepting and being operated by this unlimited variety of generic, standardized cylinders. This permits the padlock or groups of padlocks to be keyed alike, master-keyed or rekeyed in any manner, to be operated by keys compatible with other keying systems in general use, accomplishing goals of security and convenience by not requiring a separate key type for padlocks unless desired by the user. By incorporating a field selectable, dual function mechanism into such a universally adaptable padlock, no longer requiring two separate function padlocks to be inventoried, a much higher degree of standardization is achieved.
A further object of the invention is to provide a dual function padlock with an easy to use, dual function mechanism, a removable, re-keyable cylinder mechanism which does not affect the appearance or functioning of the padlock, which is simple to operate and service, which is inexpensive, which greatly enhances the security, convenience and safety features of the padlock to which it is applied, and which is otherwise particularly well suited for the purposes described. Further objects and advantages of the invention will become apparent from a consideration of the drawings and accompanying description thereof. Variations and modifications may be effective without departing from the spirit and scope of the novel concepts of this disclosure.